137 lines
3.8 KiB
C
137 lines
3.8 KiB
C
/** @file
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* IPRT - Generic Work Queue with concurrent atomic access.
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*/
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/*
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* Copyright (C) 2013-2023 Oracle and/or its affiliates.
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*
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* This file is part of VirtualBox base platform packages, as
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* available from https://www.virtualbox.org.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, in version 3 of the
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* License.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses>.
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*
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* The contents of this file may alternatively be used under the terms
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* of the Common Development and Distribution License Version 1.0
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* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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* in the VirtualBox distribution, in which case the provisions of the
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* CDDL are applicable instead of those of the GPL.
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*
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* You may elect to license modified versions of this file under the
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* terms and conditions of either the GPL or the CDDL or both.
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*
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* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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*/
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#ifndef IPRT_INCLUDED_queueatomic_h
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#define IPRT_INCLUDED_queueatomic_h
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#ifndef RT_WITHOUT_PRAGMA_ONCE
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# pragma once
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#endif
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#include <iprt/types.h>
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#include <iprt/asm.h>
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/** @defgroup grp_rt_queueatomic RTQueueAtomic - Generic Work Queue
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* @ingroup grp_rt
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*
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* Implementation of a lockless work queue for threaded environments.
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* @{
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*/
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RT_C_DECLS_BEGIN
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/**
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* A work item
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*/
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typedef struct RTQUEUEATOMICITEM
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{
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/** Pointer to the next work item in the list. */
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struct RTQUEUEATOMICITEM * volatile pNext;
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} RTQUEUEATOMICITEM;
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/** Pointer to a work item. */
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typedef RTQUEUEATOMICITEM *PRTQUEUEATOMICITEM;
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/** Pointer to a work item pointer. */
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typedef PRTQUEUEATOMICITEM *PPRTQUEUEATOMICITEM;
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/**
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* Work queue.
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*/
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typedef struct RTQUEUEATOMIC
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{
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/* Head of the work queue. */
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volatile PRTQUEUEATOMICITEM pHead;
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} RTQUEUEATOMIC;
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/** Pointer to a work queue. */
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typedef RTQUEUEATOMIC *PRTQUEUEATOMIC;
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/**
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* Initialize a work queue.
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*
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* @param pWorkQueue Pointer to an unitialised work queue.
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*/
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DECLINLINE(void) RTQueueAtomicInit(PRTQUEUEATOMIC pWorkQueue)
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{
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ASMAtomicWriteNullPtr(&pWorkQueue->pHead);
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}
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/**
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* Insert a new item into the work queue.
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*
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* @param pWorkQueue The work queue to insert into.
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* @param pItem The item to insert.
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*/
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DECLINLINE(void) RTQueueAtomicInsert(PRTQUEUEATOMIC pWorkQueue, PRTQUEUEATOMICITEM pItem)
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{
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PRTQUEUEATOMICITEM pNext = ASMAtomicUoReadPtrT(&pWorkQueue->pHead, PRTQUEUEATOMICITEM);
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PRTQUEUEATOMICITEM pHeadOld;
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pItem->pNext = pNext;
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while (!ASMAtomicCmpXchgExPtr(&pWorkQueue->pHead, pItem, pNext, &pHeadOld))
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{
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pNext = pHeadOld;
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Assert(pNext != pItem);
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pItem->pNext = pNext;
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ASMNopPause();
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}
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}
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/**
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* Remove all items from the given work queue and return them in the inserted order.
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*
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* @returns Pointer to the first item.
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* @param pWorkQueue The work queue.
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*/
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DECLINLINE(PRTQUEUEATOMICITEM) RTQueueAtomicRemoveAll(PRTQUEUEATOMIC pWorkQueue)
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{
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PRTQUEUEATOMICITEM pHead = ASMAtomicXchgPtrT(&pWorkQueue->pHead, NULL, PRTQUEUEATOMICITEM);
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/* Reverse it. */
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PRTQUEUEATOMICITEM pCur = pHead;
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pHead = NULL;
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while (pCur)
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{
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PRTQUEUEATOMICITEM pInsert = pCur;
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pCur = pCur->pNext;
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pInsert->pNext = pHead;
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pHead = pInsert;
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}
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return pHead;
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}
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RT_C_DECLS_END
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/** @} */
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#endif /* !IPRT_INCLUDED_queueatomic_h */
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